Imaging characteristics of a-Se based hybrid-type flat panel detector using high resolution phosphor screen
Byung-youl Chaa, Dae-woong Sonb, Min-seok Yunb,
Ji-koon Parkc, Chi-woong Munb, and Sang-hee Namb*
aGimhae Biomedical Industry Supporting Center, Gimhae, Korea
bRadiation Image Laboratory, Inje University, Gimhae, Korea
cR&D Center of Listem, Seoul, Korea
In previous study, our research group has developed a flat panel type radiation imaging detector using amorphous selenium (a-Se). This paper shows the results of fundamental experiments for the development of a new hybrid-type flat panel radiation detector combining a europium doped gadolinium oxide (Gd2O3:Eu) phosphor layer and an a-Se detector. The prototype detector was developed by forming a thick Gd2O3:Eu on the surface of the active-matrix flat panel detector combined with a thin a-Se layer. The active area of this detector is 8.5 inch × 7 inch, the pixel pitch is 139 m and the detector resolution is 1536 × 1280. X-ray sensitivity, dark current, and modulation transfer function (MTF) were measured to evaluate the imaging performance of the detector. From the experimental results, the dark current density was 300 pA/cm2, X-ray sensitivity was 5.24 nC/cm2-mR, and the measured MTF showed 0.42 at 2 lp/mm. Our detector can obtain higher good x-ray images compared to conventional detectors and as well enables the enhancement of image lag and low voltage operations by reducing the thickness of a-Se layer which is currently several hundreds micron thickness. For the imaging performance, full-size imaging results of phantom and diagnostic images were obtained. It shows the prototype detector gives reasonable medical quality images.
This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST) (R01-2006-000-11062-0).
* corresponding author e-mail: nsh@bme.inje.ac.kr
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